1. Field of the Invention
The present invention relates generally to bats for striking a ball and in particular to hybrid material baseball bats.
2. Description of the Related Art
Wooden bats are most popularly used because they are the cheapest ones. However, wooden bats have numerous drawbacks, such as heavy weight and bad equilibrium. Furthermore, a wooden bat is weak and easy to break, and produces severe shocks when hitting the ball. Also, as wooden bats lose moisture and dry out, they lose strength and breakage increases.
More recently, beginning in the mid 1970's, aluminum baseball bats captured a large majority of the market share versus wood bats. In comparison to wooden bats, aluminum bats are relatively lighter in weight, and have an ideal equilibrium. Therefore, the performance of aluminum bats is superior to conventional wooden bats, and aluminum bats are more durable than conventional wooden bats. Further, the price of aluminum bats is reasonable. However, aluminum bats produce shocks, noises and dents at barrel when hitting the ball.
Recently as well, beginning in the late 1980's, bats made of polymer composite materials, such as fiber reinforced plastic (FRP) materials, have been developed. The objective of FRP bats is to improve either bat performance and/or durability. However, the problem is that FRP bats are too expensive to get a popular use.
To improve the drawbacks of the prior art bats, a hybrid material baseball bat had been proposed in U.S. Pat. No. 6,929,573 to the inventor of the present invention. According to this prior proposal, the handle and barrel are separate structural components. Further speaking, the prior art hybrid material baseball bat has a bat body combined by a wooden barrel portion and a PU (polyurethane) handle portion and a FRP core embedded in the bat body. In practical use, the performance of the hybrid material baseball bat is undoubtedly better than that of the conventional baseball bats made of wooden, aluminum, or polymer composite materials. However, the inventor of the present invention found that upon striking a pitched ball, the barrel portion of the hybrid material baseball bat is responsively flexed or bowed along its entire length from the distal end to the top end thereof. Thus, the distal end of the barrel portion easily breaks due to stress concentration produced during the striking moment.
Thus, there is a need in the art for a hybrid material bat having enhanced reinforcement properties, but without the drawbacks of the bat disclosed in U.S. Pat. No. 6,929,573.